The present invention is directed to a strap joint rotator. More particularly, the present invention is directed to a strap joint rotator having a pinch wheel with a pivot linkage used with a strapping machine for compressible materials.
Strapping machines are known for securing straps around compressible loads such as cotton bales or other textile materials. To properly contain the bales, multiple straps are often used, e.g., fed, tensioned and sealed around the load, to create the baled load. Typically, such bales are strapped with plastic strap material.
A strapping machine that is used to conform the bale includes a frame on which the various strapping components are mounted. Several separate but interdependent feed and sealing or strapping heads, strap chutes and other components for positioning the multiple straps around the load are mounted to the frame. Each strapping unit operates in conjunction with each other unit so that the strapping occurs simultaneously at each of the several units. In this manner, the strapping operation is carried out in an efficient and time effective operational mode.
The baling machine includes a hydraulic press that compresses the bale prior to strapping the bale. As such, with the bale compressed prior to strapping, the bale is much more stable. An upper or compression platen forms part of the upper strap chute leg and the strapping components are mounted within a side leg of the strap chute. To effect baling, the upper platen contacts and compresses the load (which completes or closes the strap chute around the load), strap is fed through a sealing head, through the chute around the load, and back to the sealing head. At the sealing head overlapping courses of strap are sealed to one another, the strap is cut from its source (supply) and the compression platen is moved away from the bale to allow the bale to expand.
As the compression plate or platen is released, the material expands to “fill” the loop created by the sealed strap. As such, the expanding material creates a stress (a strain) in the strap. The stress is higher in the direction of expansion of the load. Moreover, the side of the bale is often that portion of the bale that is the “bottom” of the load for purposes of shipping, handling and storage. As such, given that the seal is formed at the side of the bale, the seal may be at that portion of the strap that is in a higher stress area and is in contact with the ground or other object and can possibly be damaged.
To address these concerns, one strapping (baling) machine is configured with a device that repositions the strap on the load. The device, which is a strap joint rotator, repositions the strap to relocate the seal along the bottom or top of the load to reduce the stress that is exerted on the strap joint. Such a strap joint rotator uses multiple driven assemblies, mounted to a shifting carriage. The carriage moves the assemblies into and out of the strap path subsequent loop formation and prior to expansion of the load. Such a strap joint rotator is disclosed in Bullington, U.S. patent application Ser. No. 11/782,120, which application is commonly assigned with the present application and is incorporated herein by reference.
In this arrangement, the rotator assemblies are mounted to a carriage that reciprocates all of the assemblies into and out of the strap path. Although such an arrangement has been found to work well for rotating the strap joint, the assemblies are large and relatively heavy and can exert unneeded stresses on the strapping machine. Moreover, the laterally moving rotator assemblies can inadvertently move the straps laterally, out of the strap path.
Accordingly, there is a need for a multi-head strapping machine for compressible loads that includes a strap joint rotator that exerts lesser stresses on the strapping machine. Desirably, such a strap joint rotator facilitates and assists in maintaining the strap joint aligned in the strapping portion of the machine. More desirably, such a strap joint rotator is of a sufficiently small profile to minimally, if at all, impact the machine size.